Spring boot项目集成Sharding Jdbc

环境

jdk：1.8
framework： spring boot， sharding jdbc
database： MySQL

搭建步骤

1. 在pom 中加入sharding 依赖

<dependency>
    <groupId>io.shardingjdbc</groupId>
    <artifactId>sharding-jdbc-core-spring-boot-starter</artifactId>
    <version>2.0.3</version>
</dependency>

2. 将原来的 spring DataSource 注释掉，加入 sharding 的配置

sharding:
  jdbc:
    datasource:
      names: ds_0,ds_1
      ds_0:
           type: com.zaxxer.hikari.HikariDataSource
           driver-class-name: com.mysql.jdbc.Driver
           jdbc-url: jdbc:mysql://sharding0
           username: mams_test
           password: mams_test
      ds_1:
           type: com.zaxxer.hikari.HikariDataSource
           driver-class-name: com.mysql.jdbc.Driver
           jdbc-url: jdbc:mysql://sharding1
           username: mams_test
           password: mams_test
    config:
      sharding:
        default-data-source-name: ds_0
        tables:
            task:
                actual-data-nodes: ds_${0..1}.task
                database-strategy:
                    inline:
                        sharding-column: id
                        algorithm-expression: ds_${id % 2}
                key-generator-column-name: id
            reverse_display:
                actual-data-nodes: ds_${0..1}.reverse_display
                database-strategy:
                    inline:
                        sharding-column: task_id
                        algorithm-expression: ds_${task_id % 2}
                key-generator-column-name: id
        props:
            sql.show: true

注：
这个配置只是针对分库，sharding jdbc 还支持读写分离，主从等模式，具体能够看文档sharding jdbc configuration

faq

1. 只有网友的分享例子，没有文档

sharding jdbc 的连接 shardingjdbc.io 访问是不可用的，在码云上找到了一份文档，地址是sharding-jdbc-doc

2. spring boot的 health check 显示为down

看了一下 DataSourceHealthIndicator 类的实现，要求 select 1 返回的大小为 1才认为数据库是健康的，可是通过分库以后，这个list size 应该了是数据库的数量，因此显示数据库为down。

能够将db 个health check关掉，配置management.health.db.enabled=false 便可。

不过这种状况下数据库若是挂掉的话注册中心是不知道的，须要定制一个本身的数据库检查类

@Component
public class CustomDataSourceHealthCheck extends AbstractHealthIndicator {
    private JdbcTemplate jdbcTemplate;
    private String databases;
    private int databaseCount;
    private String query = "SELECT 1 ";

    @PostConstruct
    public void init() {
        databaseCount = databases.split(",").length;
    }

    @Override
    protected void doHealthCheck(Health.Builder builder) throws Exception {
        try {
            List<Map<String, Object>> result = jdbcTemplate.queryForList(query);

            if (result.size() == databaseCount) {
                builder.up();
            } else {
                builder.down();
            }
        } catch (Exception e) {
            builder.down(e);
        }
    }

    public JdbcTemplate getJdbcTemplate() {
        return jdbcTemplate;
    }

    @Autowired
    public void setJdbcTemplate(JdbcTemplate jdbcTemplate) {
        this.jdbcTemplate = jdbcTemplate;
    }

    public String getDatabases() {
        return databases;
    }

    @Value("${sharding.jdbc.datasource.names}")
    public void setDatabases(String databases) {
        this.databases = databases;
    }

    public int getDatabaseCount() {
        return databaseCount;
    }

    public void setDatabaseCount(int databaseCount) {
        this.databaseCount = databaseCount;
    }

    public String getQuery() {
        return query;
    }

    public void setQuery(String query) {
        this.query = query;
    }
}

参考资料

1. Spring Boot Actuator: Health check, Auditing, Metrics gathering and Monitoring
2. Spring Boot Actuator Database Health Check
3. Spring Boot+MyBatis+MySql+Sharding-JDBC实现分库分表